1. Field of the Invention
The invention relates to a method for detecting presence of an interference source, and more particularly to a method for detecting presence of an interference source and performed by a touch sensing system.
2. Description of the Related Art
A conventional touch sensing device includes a touch sensor unit (e.g., a touch button), and a sensed signal processor operatively associated with the touch sensor unit for sensing external environment so as to generate a capacitance value. When the capacitance value thus generated exceeds a predetermined threshold value, the sensed signal processor generates a trigger signal for notification of a touch event.
The conventional touch sensing device is able to function normally when used in an environment that has certain temperature and humidity, and that is free of interference sources. However, in the presence of interference (e.g., electrostatic discharge or radiation noise from other electronic apparatuses), the capacitance value generated by the sensed signal processor may fluctuate drastically and undesirably exceed the predetermined threshold value. As a result, the sensed signal processor may generate the trigger signal without the touch sensor unit being actually triggered. Under severe circumstances, stability of electronic components to which the conventional touch sensing device outputs the trigger signal may be compromised.
In view of the above, several improvements have been proposed. One improvement involves increasing dimensions of a grounding copper foil of a substrate of the conventional touch sensing device to thereby facilitate grounding of radiation noise received by the conventional touch sensing device. Another improvement involves reducing gaps among components of the conventional touch sensing device to reduce propagation of radiation noise from interference sources through the conventional touch sensing device, thereby reducing interference of the radiation noise upon the conventional touch sensing device. Additionally, the components of the conventional touch sensing device may be made from materials that are resistant to radio-frequency (RF) radiation and static electricity.
However, although the abovementioned improvements are effective to a certain extent, they may suffer from other drawbacks. For example, the dimensions of the grounding copper foil may not be adjusted dynamically based on intensity and duration of interference detected by the conventional touch sensing device. Moreover, reducing the gaps among the components may result in a substantial change in appearance of the conventional touch sensing device, which may lead to compromised aesthetics. Furthermore, the abovementioned improvements may increase cost of manufacture.